The invention relates to a stereomicroscope or to an additional element for a stereo-microscope with the ability to switch between different observation modes of which one is a stereoscopic observation mode through a stereo lens and the other a binocular monoscopic observation mode through a compound lens, the stereo lens and the compound lens being rotatably supported in a switching device in the stereoscopic beam path, and a prism arrangement being provided which during observation through the compound lens combines the two beam paths to form a single beam path.
Such a stereomicroscope is described in US-A1-2002/0034001 published Mar. 21, 2002. This known stereomicroscope, in the direction of an observation beam path, includes a binocular tube and an automatic prism displacement mechanism with a binocular beam splitter that can be displaced by means of a control cable for the purpose of linking the binocular tube with either both stereoscopic observation beam paths or with just one of the two observation beam paths. This stereomicroscope also includes a microscope body accommodating the stereoscopic observation beam paths and a switching device rotatably supported on a microscope holder for a microscope body. The switching device holds a stereo lens and two compound lenses.
The microscope body, in turn, is supported on a focus-adjusting mechanism so as to be displaceable in a direction oblique to the observation beam paths. The displaceability is required to be able, in the use position, to place both the stereo lens and each compound lens centrally over the object. Because the compound lens comes to rest underneath one of the two stereo observation beam paths, however, such a displacement must amount to one-half the distance between the axes of the observation beam paths when it is desired to position the observation beam in the two observation modes relatively equally to the object. In the use position, all cited lenses are thus parcentric and parfocal. The displacement of the microscope body on its focus-adjusting mechanism is brought about by a gear that automatically causes the displacement as a function of the position of the switching device. The gear, in turn, is connected to the control cable which in turn acts on a lever mechanism with which the binocular beam splitter can be displaced.
The known microscope thus involves a complicated design with two gears and a cable connection between them. The microscope is also integrally configured, to the extent that it shows a priori this functionality of the switchable observation possibilities and that it cannot give up this functionality and thus the gears, the binocular beam path splitter and the displaceability relative to the focus-adjusting mechanism, namely that to achieve this functionality a conventional stereomicroscope can only be reconfigured but not retrofitted. In other words, this prior art does not relate to an additional element for a stereo-microscope.
Moreover, control cables are components that are not thought to be particularly reliable so that, for example, optionally they must be readjusted or serviced.
This known microscope is provided with a fluorescence excitation illumination which makes it possible to make both stereoscopic observation and fluorescence observation through a compound lens. Here, in the case of incident fluorescent light excitation, the fluorescent light passes through the right partial stereo beam path. This can be disadvantageous, because in this beam path autofluorescence phenomena can occur or such phenomena must be prevented by use of special measures. In particular, the induced fluorescence illumination reduces the contrast reflection of the fluorescent object. Although a second fluorescence excitation illumination is also provided, this illumination is directed onto the object as transmitted light illumination via a stand base of the microscope and is not available for incident light illumination.
Additionally, EP patent publication EP-B1-170857 describes a microscope with a binocular tube wherein by means of a compound lens it is possible to switch a stereomicroscope from normal stereoscopic observation to binocular observation. The drawback of such a configuration is that it does not allow compensation for a misalignment when during binocular observation the object field is changed to an object field under stereoscopic observation. To this extent, this prior art is less appropriate from a practical standpoint than is the solution according to the afore-said prior art with automatic compensation of a misalignment. This known configuration provides no solution for observations in fluorescent light.
Although EP-B1-170857 thus also discloses a stereomicroscope with a switching device for a compound lens and a stereo lens on a stereomicroscope, a switching device is not provided with a gear and does not allow automatic compensation for misalignment. Furthermore, this known configuration is not provided with a displaceable carrier. In view of the lack of any means for compensating for misalignment and especially the lack of a displaceable carrier, it could therefore not be obvious to mount a binocular beam splitter between a carrier and a compound lens, for purposes of compensation. Moreover, the use of structure as described in EP-B1-170857 would have resulted in loss of parcentricity so that a mere takeover of the known arrangement not could not be obvious but would not have led to the desired result of overcoming disadvantages in the prior art.
EP-B1-167926 also reveals a binocular tube microscope that permits lateral displacement of an optical system carrier so that the axis of the lens can be brought into coincidence with the axis of a zoom channel. From this prior art, too, no teaching can be derived concerning an improvement over prior art patent publication US-A1-2002/0034001.
EP-A1-1010030 discloses a system for stereoscopic observation in incident fluorescent light with a particularly advantageous third zoom channel through which the illumination beam path is guided. This system suppresses the disturbing autofluorescence, but does not provide a basis for selectively observing objects through a stereo lens or through a compound lens.